Fermentation of Carcinus Maenas as a Method of Waste Stream Valorization

The European green crab, Carcinus maenas, is an aggressive invasive species of green crab that has had severe ecological and economic effects to the North American East Coast since the early 1800s. The green crab has disrupted entire ecosystems, particularly in the Gulf of Maine, due to its eating and uprooting of eel grass. The disruption of this plant reduces coastal habitats for bivalves and other coastal marine life. The green crabs have also been found to prey on juvenile lobsters and bivalve mollusks, disrupting both the ecosystem in the Gulf of Maine and the seafood economy dependent on lobsters and soft-shell clams. With the changing climate and consistent increases in the ocean temperature, the number of crabs killed by the cold, winter temperatures has been steadily decreasing. The establishment of a green crab fishery for the sale of soft-shell crabs has been identified as a method to control the growing population since the crabs are too small for hard-shell culinary use. However, most crabs fished cannot be sold as soft-shell, creating a large amount of biomass. The biomass can currently only be sold to lowvalorization waste streams such as compost, bait, or animal feed. In order to sustain green crab fisheries, a high-value waste stream valorization needs to be established. Fish sauce is a clear, brown, fish-flavored condiment that is traditionally spontaneously fermented from under-utilized fish species and salt. Fish sauce originated in Asia, but has been fermented in many places throughout the world including Rome, South America, and Africa with slight variations to the formulation depending on location and starting material. Since this fermentation is spontaneous it relies on the proteolytic activity of endogenous enzymes and proteolytic bacteria to break down proteins into amino acids. One of the most common fish species used for the fermentation of fish sauce is the anchovy, which has a protein content of about 20%. Green crabs have a protein content of about 17%, indicating that green crabs could be used instead of anchovies to produce a similar condiment. The data from this work showed that when fermented at a temperature of 24°C at a salt content of 20-30%, a green crab fermented condiment can be produced that is chemically comparable to commercially available fish sauce products. Fermentation temperatures of 30°C, 37°C, and 50°C were investigated to provide guidance for temperature control. A temperature of 30-37°C with a salt content of 20% and a 90 day fermentation time was suggested based on this data, but a temperature of 24°C or 50°C will still produce a viable product. The most abundant families of bacteria throughout the course of the fermentation, regardless of fermentation temperature or time, were Rhodobacteracea, Saprospiraceae, and Hyphomonadaceae, all of which contain salt-tolerant proteolytic genera isolated from marine sources. The creation of a viable fermented crab sauce product creates a high-value waste stream for green crab fishers, thus opening the doors to start economical large-scale fishing of green crabs on the North American East Coast

Pepper pectin methylesterase inhibitor protein CaPMEI1 is required for antifungal activity, basal disease resistance and abiotic stress tolerance

Pectin is one of the main components of the plant cell wall that functions as the primary barrier against pathogens. Among the extracellular pectinolytic enzymes, pectin methylesterase (PME) demethylesterifies pectin, which is secreted into the cell wall in a highly methylesterified form. Here, we isolated and functionally characterized the pepper (Capsicum annuum L.) gene CaPMEI1, which encodes a pectin methylesterase inhibitor protein (PMEI), in pepper leaves infected by Xanthomonascampestris pv. vesicatoria (Xcv). CaPMEI1 transcripts are localized in the xylem of vascular bundles in leaf tissues, and pathogens and abiotic stresses can induce differential expression of this gene. Purified recombinant CaPMEI1 protein not only inhibits PME, but also exhibits antifungal activity against some plant pathogenic fungi. Virus-induced gene silencing of CaPMEI1 in pepper confers enhanced susceptibility to Xcv, accompanied by suppressed expression of some defense-related genes. Transgenic ArabidopsisCaPMEI1-overexpression lines exhibit enhanced resistance to Pseudomonas syringae pv. tomato, mannitol and methyl viologen, but not to the biotrophic pathogen Hyaloperonospora parasitica. Together, these results suggest that CaPMEI1, an antifungal protein, may be involved in basal disease resistance, as well as in drought and oxidative stress tolerance in plants

Use of Invasive Green Crab Carcinus maenas for Production of a Fermented Condiment

To control the population of an invasive species of green crab, we investigated the feasibility of producing a fermented crab condiment. Commercial fermented fish condiments were tested to assess variability in the marketplace and to identify targets for lab-fermented sauces. Finely chopped crab was combined with 100 mg g−1, 200 mg g−1, or 300 mg g−1 NaCl, and spontaneously fermented for up to 120 days. Chromatographic analysis revealed that histamine content was not a safety concern as all treatments were below the current U.S. legal threshold (50 mg 100 mL−1). The majority of microbial and physicochemical properties measured within salt level (proteolytic bacterial population, total volatile basic nitrogen (TVBN), amine nitrogen, water activity, moisture, and biogenic amines) were statistically unchanged between days 60 and 120 of fermentation, suggesting that most of the biochemical changes happened early in the fermentation. While the production of a fermented condiment was successful and could represent an opportunity for the valorization of this invasive species, additional work is needed to accelerate the process and further understand the dynamics of the early fermentation stages